Abstract:The social network among farmers serves as a key access for agricultural innovation diffusion (AID). So how do strong ties and weak ties affect AID under the grade structure in China? And which ties mean more to AID? Based on interview and questionnaire about growing organic vegetables in greenhouse, this paper investigates farmers’ decision model in the course of adopting certain agricultural technology and collects related data on strong and weak ties. Based on the empirical study, this research uses agentbased modeling and simulation (ABMS) to explore the role of strong and weak ties at a systematic level. Results show that increasing the quantity of social ties and elevating the level of mutual benefit and mutual help in technology transformation can improve AID significantly, thus calling for the positive role of strong ties. However, weak ties can also be more effective by providing adoption signal for network members. These results explain the underlying mechanism of AID and have important implications for facilitating AID.